Many commercial laundry machines are designed to handle a heavy load of clothing to be cleaned. Due to the large capacities of the machines, special attention has to be given to the structural strength and operational controls of the machines to ensure their proper and safe operations.
In particular, load balancing is an important concern for front-loading washer/extractor-type laundry machine (hereinafter referred to as “washer”). A washer typically has a wash drum for receiving a laundry load, and in a front-loading washer the drum is mounted to rotate around a generally horizontal axis. After the washing and rinsing cycles are done, water is extracted from the clothing by spinning the drum at a relatively high speed. For a commercial washer with a large load capacity, such as one that is rated for 150 pounds of dry clothing, the mass of the wet clothing can be quite large. To effectively remove the water from the clothing, the rotational speed of the drum during the water extraction phase can be quite high, and can generate a centrifugal force of 300 G or higher. Because the drum is horizontally mounted, there is a tendency for the clothing to sit at the lower portion of the drum before the extraction rotation begins, resulting in an imbalance in the load distribution in the drum. Due to the heavy load in the wash drum and the high rotation speed for water extraction, if the wet laundry load is not evenly distributed in the rotating drum, the imbalance can cause significant vibrations of the drum that may result in severe mechanical stress and even structural damages to the machine.